Piston for use in fluid-pressure engines



Jan. 22, 1929- C 1,699,819

E. TALBOT PISTQN FOR USE'IN FLUID PRESSURE ENGINES Filed Jan. 1927 2Sheet s-Sheet 1 Jan. 22, 1929. 1,699,819

E. TALBOT PISTON FOR USE IN FLUID PRESSURE ENGINES Filed Jan. 5, 1927 2sham-sheet 2 Patented Jan. 22, 1929.

UNITED STATES ERNEST TALBOT, OF LOWESTOIET, ENGLAND.

PISTON FOR USE IN FL'UID-PR ESSURE ENGINES.

Application filed January 3, 1927, Seriai No. 158,768, and in GreatBritain January 131926.

This invention relates to pistons for use in fluid pressure engines, ofthe kind in whlch the skirt and the head or ring-carrying portion areformed separately from one another.

The principal object of the invention 1s to provide a simpler and lesscostly method of forming the skirt and of attaching it to the head. ofthe piston, whereby, not only can the piston be made considerablylighter and more efiicient than usual, but also accurate weight andfitting of each piston is ensured without diflicnlty when largequantities of a standard size are being manufactured. A further obj setis to insure a resilient contact of the skirt with the cylinder walls toadapt itself tochanges of temperature under working conditions, and tominimize the heat transfer between the head and the skirt of the piston.

In the accompanying drawings, which show various methods of carrying outthe invention,

Figure 1 is anelevation of a complete p1ston in part-section on theaxial plane of the piston and piston pin,

Figure 2 is an end view as seen from below Figure 1, i j i Figure 3 isasectional elevation of the head part only of the piston, the plane ofthe sec tion beingtransverse to the plston pln axis,

Figure 4 is a view similar to Figure 3 showing a modified form ofhead,whilst Figure 5 is a view similar to Figure 2 showing alternativeattachment means for the skirt to a head as shown in Figure 4.

Figure 5 is a similar view to Figure 5 showing a modified attachmentmeans, i

Figure 6 is a plan of a strip of metal from which the skirt shown insection in Figure 7 is produced by rolling the strip,

Figure 8 is a fragmentary view of a strip alternative to that shown inFigure 6,

Like numerals indicate like parts throughout the drawings. v

In one method of carrying out the invention, the skirt 2 initially isconstituted by a flat disc of metal, which is pressed into the form of acup having a flat bottom, its sides constituting the actual skirtof thepiston. A cruciform hole bounded by the edges 3, 4: is pierced in thebottom of the cup, leaving four spaced inward projections or tonguesadapted, by their edges 4:, to engage the sides of the gudgeon pinbosses 5 provided in the separately formed head and giving clearance forthe small end of the connecting rod by the gaps formed between the edges3, 3 of the stitute a split skirt having the splitinclined projections.Two such pressings located with their projections in contact may besecured by the same fasteners 6 to flanges or ledges 7 (Figure 3) formedon the gudgeon pin bosses, and in this example adjacent their centralplane. Thus the inward projections or tongues serve both for theattachment of the skirt and to the head also as an accurate register intheir mutual attachment. Preferably in each construction the head isreduced in diameter below the ring-carrying portion, and the wall of thereduced portion between the bosses 5 maybe cut away as shown.

If preferred, instead of piercing a cruciformaperture in the disc, aplain slot 9 (Fig ure 5) adapted to provide for the angular movement ofthe connecting rod would suffice, and the flat parts .at the sides ofthe slot would then constitute the projecions for attachment to theunderside of the bosses 5, as shown in Figure 4, and upon the latterwould be arranged registerslO or dowels 11 adapted toengagecorresponding cut away parts 12 or perforations 13 in the projections.The flanges 7 are also employed to increase the area of support fort-heprojections and to providesufficient room for holes 14 for thefasteners, which may be of any preferred kind. Figure 5 showsalternative kinds of registers, that at 10, Figure 5, having a curvatureabout the cylinderaxis on its engagement side, whilst that at 11, Figure5 is of plain circular form. i

In the construction shown in Figure 2 and to provide for thetransmission of the side thrust from the gudgeon pin bosses to theskirt, the inner edges 4 of the projections which abut the bosses may beflanged as at 40 to provide a greater contact surface (see also Figure7). Also, the edges of the skirt, either in .the foregoing or followingconstructions, may be rounded at each end 24 so as to avoid a scrapingaction on the cylinder walls.

Asan alternative, (Figures 6 and 7) the skirts may be formed of strips15 of metal, the ends 16 of which are parallel to one another .butnot atright angles to the sides. These are bent into cylindrical form and conto the piston travel. The top and bottom edges of the skirt as thusformed are spun, pressed or otherwise bent inward to stiifen the skirtas at 24 (Figure 1), and by the formation of V or U shaped slits 17around the wall of the skirt, tongu 3s 18 are formed which are bentinwards preferably at right angles to the side of the skirt, and thusform the attachment means for connecting it with the head. If the skirtwere to be formed in two parts as in Figure 1, the tongues 18 would beformed at the ends of each, that is, at the edge of each strip 15,(Figure 8), so thatthey might abut one another and be secured togetherto the head.

In either of thelatter arrangements, certain of the tongues may berigidly secured to the heads, whilst others engage it resiliently sothat a better working engagement of the skirt in the cylinder is ensuredthroughout all changes of temperature under working conditions.

Where the projections or tongues are four in number in a single ortwo-part skirt, it will be necessary to provide apertures19 in the skirtto enable the gudgeon pin to be inserted. Alternatively, the pin may beput in place before the skirt is attached, the skirt then serving toretain the pin.

On the other hand, if the plane of the projections or tongues is belowthe axial plane of the gudgeon pin as in Figure 4, then the aperturesformed in producing the tongues, as by the slits 17 in Figure 6, may beso situated as to serve for the insertion or removal of the pin.

Obviously, if preferred, when formin the skirt by bending a strip 15into circular orm, the strip could be in two or more parts so thatthereby theskirt would be longitudinally divided at a correspondingnumber of places, the object of suchan arrangement being to obtain theresilient expanding type of skirt. In either arrangement the grain (ifany) in the skirt would be so arranged as to give maximum strength tothe tongues.

Where a large number of the same type of piston is required, the skirtmight be formed of seamless drawn tube having a finished size andpolished, and having the projections or tongues inits sides or on itsedge, but the invention is not limited to Wrought metal, as a hardcastiron skirt could be provided with the projections ready formed in thefinrangement would be that by the use ofa metal or alloy for the headhaving a greater c0- eificient of expansion than that of the skirt, thelattercould expand under the effect of the ,heat atthe points formingthe tongues owing to the grip ofthe alloy on the tongues lesseningslightly as the temperature rises.

The object of this is to ensure that the skirt will have the springimparted to it during the process of manufacture so that when assembledby fasteners to the head or placed in the casting die, the tendencywould be to spring outward against the cylinder wall. If, therefore, thehead is cast on to the inward projections or tongues, there will besufficient expansion of the alloy at points adjacent the projections toallow the latter to slip or slide outwards as the cylinder expands. Itis not intended to allow or cause the skirt to be expanded by the radialexpansion of the head.

Alternatively the converse efieet upon the skirt could be obtained ifthe material of which the head is formed has a lower coefiicient ofexpansion than the skirt, and in all the previously describedconstructions the piston headmay or may not make contact with thecylinder walls.

The skirt, whether it is made of drawn tube having a olished andfinished exterior surface or is ormed by bending a strip to circularform, may be slightly distorted, for instance, by maklng it slightlyoval so as to ensure a resilient pressure on the cylinder walls in thedirection which will prevent sla of the piston. hen the skirt is formedof drawn tube, 1t may comprise two parts as are shown in Figure 1, andthe tongues may be formed at the meeting edges ofthe two tubes in themanner shown at 1.8, Figure 8, for the fiat strip, As before the tongueson one part of theskirt can register with those upon the other, so thatthe same fastenerswillserve for both. Such a construction is one whichis peculiar- 1y suited for the economical production of a number ofsimilar pistons, particularly where uniformity of weight is essential.

The method herein describedfor the fory mation of. the skirt may beappliedto such pistons as are formed with a waist. Thus each portion ofthe skirt may be made from a flat disc, and the bottom edge may bebottled or spun-in so that clearance is provided and there is little orno interference with the oilfilm on the cylinder wall.

In any of the constructions shown, the junction between the ring-carryinportion of the head and the adjacent end of the skirt may be utilized toprovide a groove for a piston ring, as is shown at 20 in Figure 1.

The principal advantages derived from the foregoing constructions are(13 The skirt may be formed from polished material so that grinding orother machining of the outersurfaces is avoided.

(2) The attachment of the skirt and head may be such that a resilientpressure exists between the skirt and the cylinder walls, thuspreventing slap and taking up wear, although I am aware that a likeresulthas been obtained by making the skirt of any ordinary pistonslightly larger and thereafter splitting it to enable it to enter thecylinder bore.

(3) The skirt can be assembled and attached to the head in a jig orfixture correspending to a cylinder, so that subsequent I finishing orfitting is avoided.

From the foregoing it will be seen that it is possible to manufacturerapidly and economically pistons which will require no subsequentfitting in the cylinders and will have substantially the same Weight asone another when manufactured What I claim as my invention and desire tosecure by Letters Patent of the United States is 1. In a piston for afluid pressure engine, the combination of a head, a skirt formedseparately from the head and spaced projections around the skirt adaptedto form the connecting means with the head, said projections beingformed in the Walls of the skirt and thereafter bending the tonguesinwardly to form the projections substantially as set forth.

2. A piston as claimed in claim 1, in which the skirt is formed from astrip of metal bent into circular form, the meeting edges constituting asplit in the skirt which is inclined to the axis of the piston,substantially as set forth.

3. A piston as claimed in claim 1, in which the edges of the projectionsare formed with flanges, substantially as set forth.

In testimony whereof I have signed my name to this specification.

ERNEST TALBOT.

